How to place cubes evenly around a hexagon?
An quick way to do so would be DupliVerts.

Parent the cube to your hexagon

In object settings of the hexagon set duplication to verts

Enable rotation
Now you have your corner stones:


Copy your cube and hexagon and rotate them to get the stones in between


The original cube in the middle will not show up in a render.
But you can get rid of it by making the Duply Verts real Ctrl | Cmd+Shift+A.